1. Field of the Invention
The invention generally relates to an on-board fuel cell system suited for installation on a motor vehicle, such as an automobile, and also relates to a method of controlling such an on-board fuel cell system.
2. Description of Related Art
Fuel cells are known as generating electric power by using hydrogen gas supplied from a high-pressure hydrogen-gas tank or a hydrogen-gas absorbing alloy tank. The fuel cells, which exhibit high energy efficiency, are highly expected to be used as a power source for electric vehicles, and the like.
When such a fuel cell is used as a power source for a vehicle, there is a need to install, on the vehicle, a fuel cell system that includes not only the fuel cell, but also a hydrogen gas supply, such as a high-pressure hydrogen tank or a hydrogen-gas absorbing alloy tank, and a hydrogen-gas passage through which the hydrogen gas is fed from the hydrogen gas supply to the fuel cell.
For installation on the vehicle, therefore, the fuel cell system is preferably made as compact as possible in size and as light as possible in weight. Furthermore, the fuel cell system, which handles a highly combustible or flammable hydrogen gas, is required to assure a high degree of safety.